If I were a biologist celebrating the anniversary of Charles Darwinâs theory of evolution, I might be in the Galapagos islands right now, with its exotic animals and balmy weather. But no, I am 51¶ŻÂțâs resident chemist, 2019 is the 150th anniversary of the periodic table, and I am standing in a puddle of slush and ice with a man from the Geological Survey of Sweden.
Ytterby, a village on the island of Resarö not far from Stockholm, is one of chemistryâs most important sites. It was here, in 1787, that a Swedish army officer named Carl Axel Arrhenius found a scrap of black mineral and sent it to a friend for analysis. It proved to be of singular importance: almost a tenth of the naturally occurring elements in the periodic table would eventually be discovered from rocks identified in that one village.
Today Ytterby is cold, with icy winds sweeping in off the Baltic Sea. But my guide, , does his best to keep my spirits up. In the car park outside my hotel this morning, I decline his offer of snus, a moist Scandinavian tobacco that you roll into balls and stuff under your upper lip. âItâs better for you than smoking,â he says, when I politely decline, rolling himself a piece half the size of his thumb.
Advertisement
He still has it in place 30 minutes later, when we pull up in snowy Ytterby. Now an upmarket residential area, from about 1780 people began mining here for feldspar, a mineral used to make porcelain. From the road, wooden steps lead up a steep bank to a quarry. But Jonsson ignores them and begins scrabbling up the bank, which is still littered with fragments of waste minerals from the mine: large, whitish lumps of quartz lying alongside shards of black mica.
I ask Jonsson if we can find some of the same mineral that Arrhenius found, which we now call gadolinite. He says the mineral contains traces of uranium and thorium, which means the easiest way to find it is to look for their trademark radioactive decay. He pulls out a scintillation counter, which measures radiation, and begins waving it around. After a few minutes he finds a large lump of rock that turns the detectorâs steady clicking into a high-pitched whine. âI actually canât hear it because my ears are damaged from using improvised explosives,â says Jonsson nonchalantly.
We canât be certain the rock contains gadolinite without conducting proper chemical tests, but Jonsson has an authentic sample in his backpack. Turning the rock in his hands, he tells me about its extraordinary journey.
Millions of years ago, giant bubbles of molten rock enriched with rare elements began to rise up into Earthâs crust at Ytterby, cooling as they did so. This process forced certain rare elements to the top of the bubbles, creating fractures in the rock above through which they moved upwards, forming rocks called pegmatites. This happens in places around the globe, but at Ytterby the rare elements were present in such large concentrations that they crystallised into minerals of their own, of which the gadolinite that Arrhenius found is one example.
Arrhenius sent the rock to his friend Johan Gadolin, a chemist then working in Sweden. He determined that the mineral contained a new element, now called yttrium, although it wasnât isolated until some 40 years later. Then, in 1843, another chemist named Carl Gustaf Mosander showed that the mineral actually contained three new elements, which were all named after Ytterby: yttrium, erbium and terbium. In the end, at least four more elements owe their discovery to this mineral or ones like it from the Ytterby mine: ytterbium, holmium, gadolinium and thulium. Jonsson says it is possible that others were isolated from the same mine too, but the historical record isnât all that clear.
The seven elements discovered at Ytterby are not mere chemical curiosities. Many of them form the basis of some of our most sophisticated technology. Terbium is used in materials that store energy in wind turbines. Gadolinium compounds are injected into people to help enhance MRI scans, and are promising as low energy refrigerants. Yttrium was part of the first high temperature superconductors, materials that conduct electricity with almost zero resistance.
After lunch, we take a stroll around Ytterby, where the expensive houses stand on streets named after the elements. A particularly fancy-looking residence is on the junction of GruvĂ€gen and TantavĂ€gen (âmine roadâ and âtantalum roadâ). But there isnât much daylight left, so we jump back in the car. Jonsson steps on the accelerator and we leave chemistryâs most sacred site behind.
I say goodbye to my guide at Arlanda airport, where he jokingly warns me not to sneak any of the mineâs radioactive rocks onto the plane. I assure him I have no intention of mineral smuggling, which prompts an extraordinary anecdote about the time he snuck rocks out of Madagascar in his underpants.
Eventually, and without triggering any security alarms, I get on the plane. It has been a cold, windy trip far from the tropical paradise of the Galapagos, but I canât help but feel a quiet thrill. After all, this is the most famous village on the periodic table.
